The Winden Caves are an intricate system of caves without any touristic activity. They contain the portal that allows the characters in Dark to travel through time. This portal is located right under the bunker. The caves' main entrance is located in the forest and the other known entrance is near the Winden Nuclear Power Plant. These were once connected, but this connection was sealed with a metal door, as ordered by Claudia Tiedemann in 1986.